1. Field of the invention
The present invention relates to a paper loading system for use in a printer and, more particularly, to a system which may locate the opposite side edges of a loaded paper and automatically move and position the bail rollers along the paper bail to approximately opposite side rims of the loaded paper.
2. Description of the Prior Art
In FIG. 1, a prior art paper loading device is shown, which includes a platen 40 rotatably supported by a shaft diagrammatically shown by a chain line 41. Provided under the platen is feed rollers 43a, 43b and 43c which are rotatably mounted on a shaft 42 extending parallel to shaft 41. Feed rollers 43a, 43b and 43c are held against the platen with a predetermined pressure. A paper bail 44 extends parallel to shaft 41 and bail rollers 45a and 45b are rotatably mounted on paper bail 44. By the pushing force, bail rollers 45a and 45b move along paper bail 44.
When the bail is moved to a pressing position, bail rollers 45a and 45b are held against the platen with a predetermined pressure by a suitable spring (not shown) so as to hold a paper between the platen and rollers. When the bail is moved to a released position, bail rollers 45a and 45b are separated away from the platen so as to release the paper.
After loading a paper, the paper is advanced to a printing position at which the bail, which has been in the released position, is moved to the pressing position so as to hold the paper.
In this case, the bail rollers should be so organized at positions within the width of the loaded paper, and yet at places where the rollers do not affect the printing, such as at opposite side rims of the loaded paper.
In the case where the printing is carried out using different size papers, it is necessary to change the position of the bail rollers each time the paper size is changed. This is usually done manually, and is a cumbersome operation. Therefore, sometimes the operator forgets to move the bail rollers to the proper position.
If the printer is a type which uses ink, such as an ink-jet printer, the proper positioning of the bail rollers is very important. For example, if the bail rollers are positioned away from the loaded paper, the paper may be lifted off from the platen. In such a case, the ink-jet may be spotted on the paper awkwardly, resulting in a deformed character. Also, if the bail rollers are positioned against the printing area of the paper, the rollers may run over the characters just printed, resulting in an ink smear or transfer of the ink onto the rollers and back onto the paper.
Although there are a number of printers equipped with automatic paper feeding apparatus, its advantage is reduced when bail rollers are to be moved manually.